The testing of a subject's breath to determine the amount of alcohol in the subject's blood, using an infrared detector that measures the absorption of infrared energy in the 3.3 to 3.48 micron energy region, is a well established technique, used by law enforcement and alcohol treatment centers. However, this method has a serious drawback in that the IR device can not distinguish between ethyl alcohol and acetone. Significant amounts of acetone appears in the breath of persons on stringent diets and in the breath of diabetics who are in ketosis, acidosis or diabetic coma. Courts have begun to take notice of this problem.
One of the objects of this invention is to provide apparatus and method for supplying a true measure of the alcohol content of breath containing a mixture of alcohol and acetone.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.